KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Describe how the cervical, lumbar and sacral vertebrae are suited to their functions.

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN20b

Describe how the cervical, lumbar and sacral vertebrae are suited to their functions.

answers

 Cervical vertabrae

Vertebraterial canals for passage of ( vertebral) artery; atlas has ( broad) surfaces for articulation with condylyses of skulls to permit nodding
Axis has adenoid process/ protein Centrum to permit rotary/ turning act as a pivot for atlas/ skull/ movement of atlas/ Branched / forked/ short/ broad transverse processes, for attachment of ( neck) muscles; ace zygopophysis, for articulation between vertebrae ( acc. Vertebraterical canals and zygopophogen if shown on a diagram of the vertebrae
Has a short reduce neural spine, for attachment of ( neck) muscles, has wide / larger neural canal; for passage of spinal cord/ alternatively has wide neural for protection of spinal cord.

Lumbar

Broad/ long/ neural spine for attachment of ( powerful back) muscles long/ large/ well development/ transport processes for attachment of muscles ( that maintain posture and flex the muscles)
Has metamorphosis and hypothesis for muscle attachment large/ thick centrums for support
Prezygapophysis/ post/ zygapophysis for articulation between vertebrae ( acc. Anapophysis for hypopyses)

Sacral Vertebrae

Anterior vertebrae has a well developed transverse process, which are fused to the pelvis girdle/ articulate with pelvic girdle
Vertebrae fused, for strength transmit weight of the stationary animal to the rest of the body.
Sacrum has a broad base/ short neural spine; for attachment of (back)

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Name three types of skeletons found in multicellular animals

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN20

Name three types of skeletons found in multicellular animals

answers

Hydrostatic
Exoskeleton
Endoskeleton

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Describe the role of hormones in the growth and development of plants.

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN19

Describe the role of hormones in the growth and development of plants.

answers

Indole acetic acid/IAA/ Auxins

Promote cell division tropic responses, ( accept cell division in cambium)
Promote formation of absecission layers/ bring abrupt leaf – fall
Promote fruit formation ( parthenocarpy)
Promotes cell differentiation ( of vascular tissue)
Causes apical dominance/ inhabit growth and development of lateral buds
Promote growth of adventitious roots ( on stems)
IAA + cytokine induce formation of callus tissue ( during healing of wounds)

GIBBECETINS ( accept GA3)

Promotes cell division / cell elongation in dwarf varieties
Parthenocapy/ initiating formation of IAA/ setting of fruits after fertilization
Formation of side branches ( of stems) and dormancy ( in buds); inhibit growth of adventitious roots.
Activates ( hydrolytic) enzymes during germination/ promotes germination of seeds/ breaks seed dormancy.
Affects leaf expansion and shapes / retard leaf absecission

CYTOKININS’

Accept any correct example kinetin 8 zeatin
Breaks dormancy ( in some species); promotes flowering in some species
Promotes cell division ( in presence of IAA)
Stabilizes proteins and chlorophyll
Promotes root formation
Low concentration encourages leaf senescence/ high concentration protein increased cell enlargement
Promotes flowering ( in some species)
Ethylene / Ethene / C2114 ( reject ethane)
Stimulate lateral bud development
Ripening of bananas/ fruits
Induces thickening of stem/ inhabits stem elongation
Promotes germination of certain seeds/ acc promotes flowering in pineapples
Causes abscission pf leaves/ fruits/ leaf fall abscisic acid / ABA
High concentration of ABA stomata closure ( by interfering with uptake of potassium ions
Inhibits germination/ growth of embryo/ cause seed dormancy
Causes abscission of leaves/ fruits / leaf fall
Inhibit elongation growth, inhibit sprouting of bud/ induces dormancy in buds ( accept Dormin causes/ dormancy in buds/ seeds

Traumatin

Heal wounds by callus tissue formation

Florigens

Promote flowering

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K.C.S.E Biology Q & A - MODEL 2002PP1QN18

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN18

Two person X and Y drunk volumes of concentrated solution of glucose. The amount of glucose in their food was determined at intervals. The results are shown in the table below:

a) On the grid provided, plot graphs of glucose level in blood against time on the same axes.
b) What was the concentration of glucose in the blood of X and Y at the 20th minute?
X = 120 + -3)
Y = 140 +-3)
c) Suggest why the glucose level in person X stopped rising after 30 minutes while it continued rising in person Y.
d) Account for the decrease in glucose level in person X after 30 minutes and person Y after 60 minutes (3 minutes)
e) Name the compound that stores energy released during oxidation of glucose.
f) Explain what happens to excess amino acids and development of plants.

answers

(a) – For exchanged axis award maximum 3 marks for points x identity
The scale must however be correct. For graphs on separate axis mark both and award the highest mark.
(a) Axis = 2
(b) Scale = 1
(c) ( plotting) = 1
(d) curves) = 1
(b) X = 120 + -3)
Y = 140 + -3
(c) Person X is capable of regulating glucose while person y is likely to be diabetic.
X – Insulin
(d) X insulin released, excess glucose is converted into glycogen ( in liver) must be mentioned if insulin is not mentioned
Y Insulin not released, thus the decline is due to glucose being released in urine.
(e) A.T.P / Adenosine triphosphate
(f) Deaminated; resulting in formation of ammonia
Ammonia combines with CO2 to form urea ( and H20); Urea is passed out in Urine carbohydrate group is oxidized/ stored as glycogen

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State four advantages of vegetation propagation.

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN17

State four advantages of vegetation propagation.

answers

Early maturity/ short life span
Good qualities of parents are retained
Independent of fertilization/ pollinated dispersal
Large areas covered in a short time have large store of food

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Give a reason for grafting in plants

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN17

Give a reason for grafting in plants

answers

Plant with desired qualities is able to grow on an established root system which lack desired qualities

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What structures are produced by sisal for vegetative propagation?

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN17

What structures are produced by sisal for vegetative propagation?

answers

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K.C.S.E Biology Q & A - MODEL 2002PP1QN16

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN16

The diagram below represents part of phloem tissue.

a) Name the structures labeled R and S and the cell labeled T.
R
S
Cell labeled T
b) State the function of the structure labeled S
c) Explain why xylem is a mechanical tissue

answers

(a) R. Sieve pore
S- cytoplasmic strand, cytoplasmic filaments rej. Proto plasmic strand)
Cell labeled T
(b) Translocation (L is tied with structures)
(c) Thickened and lignified.

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K.C.S.E Biology Q & A - MODEL 2002PP1QN15

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN15

Ascaris lumbricoides in an example for an endo – parasite
a) The name Ascaris refers to
b) State the habitat of the organism
c) State three ways in which the organism is adapted to living in its habitat.

answers

(a) Genus
(b) Ileum/ colon/ duodenum/ intestines/ of humans or intestines of pig
(c) Lack of elaborate elementary canal ( simple guts) can tolerate raw corn
Thick cuticle pellicle, reject the outer covering lays many eggs
Mouthparts for sucking partly digested food

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Distinguish between divergent and convergent evolution giving example in each case.

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN14

Distinguish between divergent and convergent evolution giving example in each case.

answers

Divergent basic structural form is modified to serve different functions; e.g. vertebrate forelimbs, break structure in birds/ feet in birds’ convergent different structures are modified to pass or similar functions e.g. wings and birds and insects/ eye of human and octopus, vertebrates for humans e.g. squeal, legs of vertebrae and insects .

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State two ways in which Home sapiens differs from Homo habilis

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN14

State two ways in which Home sapiens differs from Homo habilis

answers

Standing upright/ erect posture. Higher intellectual capacity/ higher brain/bigger capacity; communication through language speech.

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What is organic evolution

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN14

What is organic evolution

answers

Emergence of present fauna and flora/ new life
Term/ species/ organisms from pre-existing forms gradually over a long period of time.

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K.C.S.E Biology Q & A - MODEL 2002PP1QN13

17/6/2020

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K.C.S.E Biology Q & A - MODEL 2002PP1QN13

The chart below shows the number of chromosomes before and after cell division and fertilization in a mammal.

a) What type of cell division takes place at Z
b) Where in the body of a female does process Z occur
c) On the chart, indicate the position of parents and gametes
d) Name the process that leads to addition or loss of one or more chromosomes.
e) State three benefits of polyploidy in plants to a farmer

answers

a) Meiosis
b) Ovary
c) parent must be the 2n top; any ‘n’ is a gamete
d) Non – dysfunctions
e) increased yields / highbred Vigor, Resistance decreases
Resistance to drought.

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